Solar tracker with movement in two axes and actuation in only one of them

ABSTRACT

According to FIG.  6 , it consists of a solar tracking device with two axes of rotation, which is actuated only in one of them by virtue of the incorporation into the mechanism of a support bar of adjustable length ( 8 ), which is articulated at its two ends and anchored via one side to the body that tracks the sun ( 4 ) and via the other side to an adjustable support ( 5 ) joined to the base of the actual tracker or to the ground. In turn, the bar is equipped with a shock-absorbing spring system ( 10 ) that allows it to be operated as a dynamic control element for the whole assembly.

The present invention relates to a solar tracking device with two axesof rotation, which is actuated in only of them, by virtue of theincorporation into the mechanism of a support bar of adjustable length,which is articulated at its two ends and anchored at one side to thebody carrying out the solar tracking, and at the other to an adjustablesupport joined to the base of the actual tracker or to the ground. Inturn, the bar is equipped with a shock-absorbing spring system thatallows it to be operated as a dynamic control element for the wholeassembly.

BACKGROUND OF THE INVENTION

Solar tracking devices with two axes (orientation movement—tracking ofthe azimuth—and inclination movement—tracking of the elevation-) areknown. These devices seek maximum energy collection from solar radiationby making the incidence of the solar rays be perpendicular throughoutthe day to the collection surface of the thermal or photovoltaic device.

The two rotations determining the orientation of the collection surfaceare carried out by means of two drive systems (they are normally gearedmotor, motorized screw, cable or lever system assemblies . . . ).

Compared with a tracker system with only one axis, the tracker with twoactuated axes is more expensive to construct and maintain and lessreliable since it incorporates more elements that can break down. Byintroducing a restriction suitably linking the two rotations, themovement in the two axes can be achieved by means of actuating thetracker in only one axis. A mechanical configuration has been devisedwhich allows carrying out this movement, the features of whichconfiguration are object of the present invention.

DESCRIPTION OF THE INVENTION

A solar tracking system with two axes is generically characterized bythe position of the axes of rotation, as is described in FIG. 1. Theaxis of rotation for the orientation movement is perpendicular to theground plane and the axis of rotation for the inclination movement isparallel to the plane of the ground. The axes are not necessarilysecant. Taking as a point of reference of the tracker the intersectionof the axis of rotation for orientation with the plane of the ground(point O), the lengths determining the position of the axes are H and D,distances from the axis of rotation for inclination to the plane of theground and to the axis of rotation for orientation, respectively. Thebody containing the tracking surface (4) thus rotates around the axis ofinclination with respect to the body (3), which in turn rotates aroundthe axis of orientation with respect to the base of the tracker (2),anchored to the ground (1).

As described in FIG. 2:

-   -   A point A, integral to the ground (1) or to the base of the        tracker (2) indistinctly, separated a distance d_(A) from the        axis of orientation, such that the plane that it defines next to        the axis of orientation is the North-South plane (5) (henceforth        N-S plane) is considered.    -   A point P belonging to the body (4), separated a distance d_(p)        from the axis of inclination, and belonging to the plane        containing the axis of orientation and perpendicular to the axis        of inclination is considered.    -   A joint between points A and P, by means of an arm (6) with        length L, articulated at its two ends by means of lashings        preventing the movements between the lashed bodies but not        rotations (ball and socket or universal joint) is considered.        Despite the oscillation of the shock-absorbing spring system,        the variation in the length of the bar can be considered        negligible averaged throughout the day.

Under these premises, it can be geometrically deduced that thetrajectory of point P is, as FIG. 3 indicates, the intersection betweenthe toroid centred in the axis of rotation for orientation, the centreof which is at a height H from the ground, with a toroid radius D and asection radius d_(p), and the sphere centred in point A of radius L. Thetrajectory of point P is symmetrical with respect to the N-S plane andthe maximum height is reached when P coincides with the N-S plane (solarmidday). It is thus achieved that the incidence of the solar rays isapproximately perpendicular to the collection surface throughout theday. Its position will depend on the angle of orientation of the tracker(considered with respect to the N-S plane), and of the geometricvariables and design of the system, in other words, H, D, d_(A), d_(p)and L.

The values of H and D will be fixed by the mechanical configuration ofthe tracker. If the value of d_(p) is also fixed to place the support ofthe articulated arm in the most suitable place (coinciding with a bar orat a point where the robustness of the system is high), the position ofthe anchoring of point A, d_(A), and the length of the bar, L, would belike design parameters. These two parameters will be calculated suchthat, for a certain period of the year (for example, summer solstice)the difference between the trajectory of the tracker and the solartrajectory is minimal. As the solar trajectory continuously variesthroughout the year, the mechanism allows adjusting:

-   -   The length of the bar which will allow, by adjusting the same to        previously calculated positions, optimizing the trajectory of        the tracker in all periods of the year.    -   The distance d_(A) from the support, always placed on the N-S        plane, to the axis of orientation will allow in the same way the        trajectory of the tracker to be optimized.

After the geometric description describing the operation of theinvention, the details of the key elements are given: The bar ofadjustable length and the adjustable anchorage support.

1. ARM OF ADJUSTABLE LENGTH: FIG. 4 describes, only by way of example,the components of the arm in its most complex configuration. It is seenin the sectioned view that at the two ends it incorporates two ball andsocket joints (1) and (2), restricting the translations between thelashed bodies, but not rotations. It also has a manually orautomatically actuated mechanical, electrical, magnetic, hydraulic orpneumatic extension-compression mechanism (3). It furthermoreincorporates a shock-absorbing spring system (4) responsible forattenuating both the forces that can act on the tracker at specificmoments (gusts of wind) and for reducing vibrations and resonances towhich the tracker might be exposed by external actions (for example,incidence of the wind). Simpler configurations not incorporating theelements for adjusting the length and/or suspension elements, dependingon the features that the tracker is to have, can be chosen.

2. ADJUSTABLE ANCHORAGE SUPPORT: FIG. 5 describes, only by way ofexample, the components of the support in its most complexconfiguration. It consists of a manually or automatically actuatedmechanical, electrical, magnetic, hydraulic or pneumatic positionadjustment device (1) of type. This device is responsible for varyingthe previously described distance d_(A) of the joining support of thearm (2), which moves with respect to the base of the assembly (3). Thissupport can totally or partially house the ball and socket or universaljoint with the arm. A simpler configuration where the support (2) is notadjustable and is directly anchored to the base of the tracker or to theground, depending on the features that the tracker is to have, can bechosen.

BRIEF DESCRIPTION OF THE DRAWINGS

To better understand what has been described in the presentspecification, explanatory drawings described below are attached hereto.

FIG. 1 describes the movements of a generic solar tracker with two axes.The tracker is made up of a base (2) anchored to the ground (1). Theorientation rotation is carried out by the intermediate body (3) withrespect to the base (2). The inclination rotation is carried out by thebody containing the collection surface (4) with respect to theintermediate body (3).

FIG. 2 describes the mechanical configuration of the invention. Theorientation and inclination rotations are linked by means of introducingan articulated arm at the ends (6), joined to a point A integral to theground (1) or to the base of the tracker (2), and to a point P, integralto the body containing the collection surface (4). Point A belongs tothe North-South orientation plane (5) which, in turn, contains the axisof orientation. The distance from A to the axis (d_(A)) can be adjusted,as well as the length of the arm (6).

FIG. 3 describes the geometric deduction of the trajectory of point P,calculated as the intersection of a sphere of radius L (length of thearm), at a distance d_(A) from the origin of reference O, and a toroidaligned with O, parallel to the plane of the ground and at a distance Hfrom the latter, with main radius D and radius of the section d_(p).

FIG. 4 describes, only by way of example, the arm of adjustable length.It incorporates at its ends two ball and socket or universal joints (1)(2), in the intermediate part a system for adjusting the length of thearm (3) and a shock-absorbing suspension spring system (4).

FIG. 5 describes, only by way of example, the adjustable anchoragesupport, integral to the ground or to the base of the tracker. Itconsists of an adjustment system (1) varying the position between thesupport (2) of the arm and the base.

FIG. 6 describes, only by way of example, a practical case for applyingthe invention in a solar tracker with two axes.

DESCRIPTION OF A PREFERRED EMBODIMENT

As indicated in FIG. 6, the solar tracker is made up of a base (1) onwhich there pivots a trunk (2) carrying out the orientation rotation bymeans of the actuation of a drive system. In turn, the structure (4)containing the collection elements pivots with respect to the trunk (2)around an axis (3).

A support formed by a fixed base (5) and a longitudinal adjustmentsystem (6) responsible for varying the location of the fixing (7) of thesupport with the joint of the arm (8) is anchored to the floor.

The arm (8) incorporates a length adjustment system (9) by means of adouble thread cylinder and a suspension system (10) formed by a springand an absorber. The ends of the arm (8) incorporate ball and socketjoints joining it with the fixing (7) of the support anchored to theground and with the fixing (11) placed on the structure (4).

1. Solar tracker with movement in two axes and actuation in only one ofthem, one of them perpendicular to the plane of the ground, called axisof orientation, and the other one parallel to the plane of the ground,and not necessarily secant with the first, called axis of inclination,incorporating a joint, by means of an arm with ball and socket oruniversal joints, placed at its ends between a support anchored to thebase of the tracker or to the ground, and the body carrying out theinclination rotation.
 2. Solar tracker with movement in two axes andactuation in only one of them according to claim 1, characterized by thefact of having in the support anchored to the base or to the ground asystem for adjusting the distance of the joint of the arm to the axis oforientation, carrying out that adjustment by means of manually orautomatically actuated mechanical, electrical, magnetic, hydraulic orpneumatic devices.
 3. Solar tracker with movement in two axes andactuation in only one of them according to claim 1, characterized by thefact of having in the articulated arm a system for adjusting the lengththereof, carrying out that adjustment by means of manually orautomatically actuated mechanical, electrical, magnetic, hydraulic orpneumatic devices.
 4. Solar tracker with movement in two axes andactuation in only one of them according to claim 1, characterized by thefact of having in the articulated arm a shock-absorbing suspensionspring system.